As the upper midwest awaits the first major snowfall of the year, our friends to the south and east continue to clean up after their early storm.
Nevertheless, snowplows in our area are ready to roll at a moment's notice " prepared to spread sand and salt. For homeowners, de-icing materials are a common method of dealing with ice and snow on driveways, walkways and streets. Unfortunately, they can be quite damaging to trees, shrubs and other landscape plants. Already stressed from a dry summer and unseasonably warm fall, salt spray may be just another blow in a long string of problems. Here are some tips to help you safely handle ice and snow this winter season:
There are five main materials that are used as chemical de-icers: calcium chloride, sodium chloride (salt), potassium chloride, urea, and calcium magnesium acetate. Calcium chloride is the material most frequently used for road and highway de-icing. Although not highly toxic, at high concentrations, it can cause plant damage. Sodium chloride (salt) and potassium chloride are not as common but are quite toxic when splashed on trees and shrubs. Urea is a fertilizer material and does not burn foliage or roots as badly as some of the other materials. However, it can run off into surface water, causing water quality problems. Calcium magnesium acetate is a newer material that does not harm plants but is rather expensive.
Salt damages plants by pulling water away from the root system. Likewise, the sodium ions then travel throughout the plant and collect at toxic levels in leaves and stems. Symptoms of salt damage include stunted yellow foliage with brown edges, a blue-green over all cast to the plant, or permanent wilting even when the soil is moist.
Unfortunately, little can be done to cure the damage caused by salt buildup in the soil. In this instance, prevention is the best medicine. Avoid piling salt-contaminated snow around trees, shrubs and flowers. Try using sand, kitty litter, or cinders for traction. Plant salt-tolerant species such as Amur and Red maples, winged Euonymus, Green ash, mooth and staghorn sumac, and Japanese yews near areas where salt is likely to be spread.
If salt contamination has occurred, flushing the area with large amounts of water this spring is the only remedy. As a general rule, six inches of water will leach out about one-half of the salt. Twelve inches will leach out about four-fifths of the salt. And 24 inches of water will leach out about nine-tenths of the contaminant. So, as you can see, this is a lengthy process.
The wonder and magic of snow quickly diminishes with the addition of de-icing materials. Unfortunately, little can be done once salt has contaminated soil along driveways, streets, and parking lots. Removing contaminated snow from around landscape plants, using less toxic materials, and planting salt-tolerant varieties of trees and shrubs are the most powerful methods of dealing with salt.
- Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.